The Northern Territory’s largest power station has undergone a significant refurbishment to cater for the ever-growing demand for electricity in the top end.
With a new US military base, a rapidly increasing population, and significant infrastructure projects now underway, it’s no surprise that the Northern Territory’s power demands have been increasing at an average rate of 4 per cent per year.
It’s been a challenging time for the territory’s electricity, water and sewerage provider, Power and Water Corporation, however the government-owned entity is now more than half-way through a five-year $1.526 billion investment program that will see them build, upgrade and maintain infrastructure in the region to cater for the new demand.
One of the pillars of the program has been a major upgrade to the territory’s largest power station on Channel Island.
Power and Water Corporation general manager generation Ian Pratt says the $120 million project involved the installation of two new Rolls Royce-built gas turbines, which were chosen due to time constraints that the project faced and the turbines’ dual capacity. The new units take the station’s turbine tally to nine.
“The turbines can run without water at 45MW at their peak efficiency, or with water injection at 55MW at the same efficiency,” Ian says.
Together the two Trent 60 aeroderivative turbines increase the capacity of the Darwin-Katherine power system by nearly 25 per cent, and breathe an extra 15 to 20 years’ life in to the 25-year-old Channel Island station.
Perhaps the most impressive aspect to the upgrade, however, was the speed in which the project was completed.
“We put the first orders with Rolls Royce for the machines in mid-2010, installation started in June 2011 with performance testing completed in late 2011,” Ian says.
“The fastest that Rolls Royce have done it themselves was a year-and-a-half.”
The gas and diesel supply systems were installed and supplied fuel in time for the units’ commissioning, while the 132kV switchyard was also extended to cater for the additional units, which are known as 8 and 9.
The speed of the installation was partly thanks to the Power and Water team managing both the design and construction of the turbines, which is unusual for a project of its scope and scale.
“We changed our philosophy of the way we build them. The project team that was responsible for all of the design and construction had the construction contract to actually do the building as well, so we took the risk and responsibility there and from that we gained some of the benefits of not having to do as much of the pre-design and contract work upfront,” Ian says.
Even more impressive is that the construction team was able to build the two turbines in record time while also dealing with some of the worst weather conditions on record.
“During the build we had the wettest rain season ever recorded in Darwin, which added quite significant challenges to the project team with regards to drainage and soil erosion,” project manager Joh Rickermann says.
These problems were largely mitigated however with Power and Water already having plans in place so that the extreme weather conditions didn’t cause any major disruptions. In the end, the weather conditions added a mere month to the building timeframe.
Inclement weather aside, there were also a variety of technical challenges that Power and Water faced during the build from cabling issues to cooling gas.
“It might sound like a small issue but the gas was cooling and evaporating due to the heavy rain and long length of pipeline,” Ian says.
“To solve the problem we actually just put a cover over the gas pipe to keep the gas warm, which saved maybe half a million in costs.”
Now fully operational, Channel Island’s two new units will provide the additional generation required to allow Power and Water to carry out maintenance on some of the older plant at the power station, in a project that is expected to take another three-to-five years to fully complete.
In the meantime, Channel Island will continue to form the centrepiece of a growing network of Northern Territory power stations that are providing for the ever-increasing needs of the country’s ‘top end’ consumers.
The new units at Channel Island
Rolls Royce-built Trent 60 aeroderivative turbines
Capacity: 45/55MW (dependent on operational configuration)
Fuel: Natural gas and diesel
Project cost: $120 million Darwin-Katherine system
peak electricity demand: 285MW
Peak demand growth: Up to 4 per cent per annum
Power and Water Corporation provides electricity, water and sewerage services to some 80,000 customers across more than 1.3 million square kilometres that make up the Northern Territory – nearly one sixth of Australia’s land mass.
The corporation’s 1000 staff work in diverse locations from remote communities to major urban centres stretching from the cyclone and storm-prone tropics of the north to the deserts of central Australia, often maintaining their critical services in extreme weather conditions and harsh environments.
A further 155 staff are contracted in remote indigenous communities and are supported by Power and Water’s Remote Operations team.
Power and Water is a government-owned corporation that was formed in 2002, after taking over from the former government utility Power and Water Authority.
At the time, Power and Water Corporation was the first Government-owned corporation in the territory.
Today it takes its gas from the Blacktip gas field, located in the Joseph Bonaparte Gulf off the Northern Territory’s north-west coast, which is expected to supply the corporation’s gas needs for at least the next 25 years.